It is many times desirable to be able to shift conveniently between alternate line feed rates when typing. With means of some types, it appears much neater on the page when a 51/3 lines per inch line feed rate is utilized while other types appear to be more ascetically related when a six lines per inch feed rate is used.
Heretofore intricate systems involving gear trains and idler gears parallel shafts, and mechanisms to engage and disengage the platen from drive feed ratchets have been used. Many of these devices are cumbersome, complex and expensive to manufacture as well as being potential sources of mechanical malfunction.
Other devices require multiple feed pawls, each individually driven in accordance with the selected feed rate and still other prior art patents illustrate varying drive ratios controlled through planetary gear change.